Apparatus for teaching telegraphy



y 1943- A. E. THO-MPSON ET AL 2,318,269

APPARATUS FOR TEACHING TELEGRAPHY Filed June 13, 1941 2 Sheets-Sheet 1 Fig. 1.

y 4, 1943 A. E. THOMPSON ETAL ,313,269

APPARATUS FOR TEACHING TELEGRAPHY FiledJune 13, 1941 2 Sheets-Sheet 2 2 F lg. 2. 4

Patented May 4, 1943 APPARATUS F03. TEACHING TELEGRAPHY Alfred Edward Thompson and Reginald Dennis Salmon, Croydon, England, assignors to Creed and Company Limited, Cro-ydon, England Application June 13, 1941, Serial No. 397,931 In Great Britain November 22, 1940 2 Claims.

- "This invention relates to apparatus for teaching telegraphy. The object of the invention is to provide a simple and cheap form of apparatus for generating telegraph signals for the purpose of training students to interpret such signals.

Such apparatus is more particularly useful for transmitting a standard series of exercises in the Morsecode of gradually increasing difliculty.

The nature of the invention will be better understood from-the following description of one embodiment thereof taken in conjunction with the accompanying drawings in which:

Figs. 1 and 2 are perspective views of the exercise transmitter, and Fig. 3 shows a detail.

The embodiment of the invention described hereinafter comprises a transmitter for signals in the Morse code, which is intended for transmission of a standard series of exercises.

The dots and dashes of each exercise are recorded as black and white marks on the circumference of a number of cylinders, the marks being arranged in the form of a screw thread or as 'a continuous circumferential line according to the length of the exercise. Each cylinder is placed as required between rotating centres in the machine and scanned by a beam of light which controls, by means of a photo electric cell, a valve amplifier. The amplifier is provided with two outputs, one output being a tone suitable for use in the headphones and the other output being rectified signals suitable for operating relays that control Morse keys.

All the exercises required for the first twelve lessons of a course of standard exercises are contained on a single cylinder, each exercise being brought into the controlling position by the movement of one lever. The thirteenth lesson of the course in transmission requires two cylinders each carrying two exercises of approximately 6 minutes duration. The course in reception comprises six lessons each requiring one cylinder carrying three exercises of approximately 2 minutes duration, each exercise being used twice to give the required exercise period of minutes. The cylinders may easily be removed and replaced by withdrawing a spring loaded plunger. When inserting a cylinder into the machine it is only necessary to lay it in a cradle and to release the plunger. The cylinders are made of moulded synthetic resin and. the dots and dashes are formed as white marks cut in the surface of the resin and filled in so that the outer surface of the cylinder is quite smooth.

Referring now to the drawings, each cylinder, as it is required, is placed in the machine between The centres l and 2 are carried in a frame IO also adapted to slide endways upon the shaft 8. The shaft 8 is provided with a screwed portion H of square form. The frame I0, however, is formed with a plain hole so that it can freely slide over the top of the thread portion of the shaft-8.

A lever 12 mounted upon the frame i8 is provided with a portion in the form of a half-nut as shown more clearly in Fig. 3 so that when the lever i2 is in the position shown in Fig. 1 the half-nut will engage with the thread and thereby cause frame 10 to move endways when the-shaft 8 is rotated. The rotation of the shaft 8 will also cause the gear 1 to rotate due to the action of the spline 9 thereby rotating the gear ii and'cylin der 5. Hence the cylinder 5 is caused to move endways whilst it rotates.

The lever l2 may however be turned through as shown in Fig. 3 whereby it is disengaged from the thread I l and engaged with a stationary rack I3. When the lever I2 is disengaged from the thread II the frame l8 may be moved endways manually to engage the lever l2 with any slot of the rack I3.

An optical condenser 14 is arranged to focus light from a lamp l5 upon a small portion of the cylinder 5. An image of the brightly illuminated portionof the cylinder 5 is focussed by means of a lens system It upon a diaphragm I! having therein a small rectangular hole. The beam of light, after passing through the hole in diaphragm I1 is arranged to be interrupted by teeth carried on the periphery of a rotating disc l9 mounted upon the shaft of a driving motor 28, Fig. 2 after which it passes into a photo electric cell I8 which is associated with a vacuum tube amplifier having an output suitable for operating relays. Alternatively, the amplifier is adapted to give a tone output suitable for use in headphones. The shaft 8 is driven from motor 20 through gearing 2| and pulley wheels 22 and 23 the diameters of which are arranged so that the spindle 8 may be driven at one or other of two speeds corresponding to 10 or 16 words per minute, the speed of 10 words per minute being used for lessons in transmission and the speed of 16 words per minute being used for lessons in reception. V

The arrangement is such that when the lever I2 is in the position shown in Fig. 1, the cylinder 5 rotates and moves endways. The beam of light from lamp l5 illuminates successively aspiral path upon which the dots and dashes of the exercise are marked so that light reflected therefrom and focussed upon diaphragm I1 is caused to operate the photo eleectric cell to produce impulses of current therein corresponding to the dots and dashes marked upon the cylinder.

The dots and dashes are recorded as white marks on a black background, the light reflected from these is chopped up by the teeth on the rotating disc 19 so that each dot and dash becomes a group of short impulses, the frequency of which is arranged to produce a tone in the valve amplifier of approximately 1,000 per second. This tone after amplification may be used for operating the headphones, or is rectified and operates a power valve for controlling relays operating a solenoid arranged under a Morse key.

Each dot on the cylinder is approximately 1 3'" in length and each dash approximately in length. The spiral traced on the circumference of the cylinder is %"1 pitch and 5" in length. The record provides for continuous transmission of approximately 60 words. Each cylinder may, however, contain more than one exercise and the transmission may be stopped at any moment.

For those exercises which comprise the transmission of a continuous series of the same letter or letters, the cylinder does not move endways whilst it rotates. is formed as a continuous ring on the surface of the cylinder and the cylinder is moved endways to engage lever 12 with a tooth of the rack l3 to bring the desired letter or group into the scanning path. 1

The cylinder may be quickly removed from the machine and replaced by pulling back centre I by means of the handle 3. A cradle underneath the cylinder locates it when it is first placed in Each letter or group of letters the machine. When the handle 3 is released to re-engage the center I with the cylinder, the cylinder is lifted slightly so as to be held clear of the cradle.

It is to be understood that the apparatus could be used to reproduce an exercise consisting of telegraph signals from a record made by a Morse inker on a sheet of paper wrapped around one of the cylinders.

In this case it will, however, be necessary to invert the signals by inserting between the photo-electric cell and the amplifier any well known form of inverting device so that the signals which are as black marks on the cylinder will be reproduced as tones or as operations of the telegraph key.

What is claimed is:

1. A telegraph signal transmitter for teaching telegraphy comprising a cylinder having representations of telegraph signals spirally arranged on its circumference, a carriage for supporting saidcylinder in operative position, means for rotating said cylinder, scanning means for scanning said representations to produce signal mounted for rotation with said cylinder, manually operable means mounted on said carriage for engaging said threaded spindle to advance said carriage upon engagement, and stop means for cooperating with said manually operable means in disengaged position to prevent endwise movement of said carriage.

2. A telegraph signal transmitter according to claim 1, wherein said manually operable means comprises a lever pivotally mounted on said carriage and having a screw thread capable of.

engaging with the thread on said shaft, and spring means for maintaining said engagement and said stop means comprises a plate having a series of notches for receiving said lever when in disengaged position.

ALFRED EDWARD THOMPSON. REGINALD DENNIS SALMON.

indications, a threaded spindle 

